Double Trouble is the third episode of Ben 10 Ominihero.
The chapter first begins with Ben and Kevin training on the Rust Bucket, where Kevin absorbs a piece of wood and Ben turns into SnowBeast for the first time. During the fight SnowBeast accidentally opens a hole on the ship's walls, causing Gwen to go after them and stop the fight. Due to the rapid change in pressure, Rook has difficulty maneuvering the ship, and SnowBeast creates an ice ramp to stop the ship on it's tracks.
During this time, the ship goes through a green fog on the planet's atmosphere, causing a humanoid creature to invade the ship. It is fought by Kevin and Gwen and is thrown off the ship by a magic hurricane, being found and knocked down by the Unknown Observer.
The team then goes through the jungle and meets Tatooobalien, who guides them to a place where there is paranormal activities happening, which turns out to be the planet's maximum security prison. On the entrance, the group is attacked by a bunch of Sonorochimp clones. After another fight, the team follows Duolion, one of the prison's guard, while Tatooobalien stays behind with Zed. They meet up with Chimutation, Metrofloris's most dangerous Mixster, and he tells them his backstory, and how he was kidnapped by Galord and turned into an Omnitant.
Ben tries to cure him, but a pair of Necronurites attack his cell, and Ben turns into XYZ to fight them. The pair lets the prisoners loose on the facility, and XYZ divides into X and Y, causing them to split up. Y is found by Gwen, Kai and Tatooobalien, while X arm wrestles Kevin on his metal form. After losing to Kevin, X agrees to come back with them, and as they rendezvous with the others, they fight with the Omnitants currently present, which is the Pyroflor, the Sonorochimp clones, the Necronurites and later Tetralillean, who is fought by Ben as Chimera and then cured of his Omnitant condition, as well as the Sonorochimps, who turned out to be Chimutation's cell partner.
- The team visits Metrofloris for the first time.
- XYZ, SnowBeast and Chimera make their first appearance.
- Ben cures Chimutation and Mouslittle from their Omnitant curse.
- It is revealed that Metrofloris is located on Battle Ben's universe
- Unknown Observer